Multi-channel flow ratio controller and processing chamber

ABSTRACT

Implementations of the present disclosure generally relate to one or more flow ratio controllers and one or more gas injection inserts in the semiconductor processing chamber. In one implementation, an apparatus includes a first flow ratio controller including a first plurality of flow controllers, a second flow ratio controller including a second plurality of flow controllers, and a gas injection insert including a first portion and a second portion. The first portion includes a first plurality of channels and the second portion includes a second plurality of channels. The apparatus further includes a plurality of gas lines connecting the first and second pluralities of flow controllers to the first and second pluralities of channels. One or more gas lines of the plurality of gas lines are each connected to a channel of the first plurality of channels and a channel of the second plurality of channels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/418,489, filed Jan. 27, 2017, which claims priority to U.S.Provisional Patent Application No. 62/403,583, filed on Oct. 3, 2016,which herein is incorporated by reference.

BACKGROUND Field

Implementations of the present disclosure generally relate to asemiconductor processing chamber, and more particularly, to one or moreflow ratio controllers and one or more gas injection inserts in thesemiconductor processing chamber.

Description of the Related Art

Semiconductor substrates are processed for a wide variety ofapplications, including the fabrication of integrated devices andmicro-devices. One method of processing substrates includes depositing amaterial, such as a dielectric material or a semiconductive material, onan upper surface of the substrate. The material may be deposited in alateral flow chamber by flowing a process gas parallel to the surface ofa substrate positioned on a support, and thermally decomposing theprocess gas to deposit a material from the gas onto the substratesurface. However, the material deposited on the surface of the substrateis often non-uniform in thickness and non-uniform in alloy or dopantcompositions, and therefore, negatively affects the performance of thefinal manufactured device.

Therefore, there is a need for an improved chamber to deposit a materialthat is uniform in thickness and in alloy or dopant compositions.

SUMMARY

Implementations of the present disclosure generally relate to asemiconductor processing chamber, and more particularly, to one or moreflow ratio controllers and one or more gas injection inserts in thesemiconductor processing chamber. In one implementation, an apparatusincludes a first flow ratio controller including a first plurality offlow controllers, a second flow ratio controller including a secondplurality of flow controllers, and a gas injection insert including afirst portion and a second portion. The first portion includes a firstplurality of channels and the second portion includes a second pluralityof channels. The apparatus further includes a plurality of gas linesconnecting the first and second pluralities of flow controllers to thefirst and second pluralities of channels, wherein one or more gas linesof the plurality of gas lines are each connected to a channel of thefirst plurality of channels and a channel of the second plurality ofchannels.

In another implementation, an apparatus includes a first flow ratiocontroller including a first plurality of flow controllers and a firstflow controller, a second flow ratio controller including a secondplurality of flow controllers and a second flow controller, and a gasinjection insert including a first portion and a second portion. Thefirst portion includes a first plurality of channels and a first innerchannel and the second portion includes a second plurality of channelsand a second inner channel. The apparatus further includes a pluralityof gas lines connecting the first and second pluralities of flowcontrollers to the first and second pluralities of channels, a first gasline connecting the first flow controller to the first inner channel,and a second gas line connecting the second flow controller to thesecond inner channel.

In another implementation, an apparatus includes a chamber including anupper dome, a lower dome, a base ring disposed between the upper domeand the lower dome, and a gas injection insert located within the basering. The gas injection insert includes a first portion and a secondportion. The first portion includes a first plurality of channels andthe second portion includes a second plurality of channels. Theapparatus further includes a first flow ratio controller including afirst plurality of flow controllers, a second flow ratio controllerincluding a second plurality of flow controllers, and a plurality of gaslines connecting the first and second pluralities of flow controllers tothe first and second pluralities of channels. One or more gas lines ofthe plurality of gas lines are each connected to a channel of the firstplurality of channels and a channel of the second plurality of channels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side cross-sectional view of a chamber accordingto implementations described herein.

FIG. 2 is a perspective view of a liner assembly that can be used in thechamber of FIG. 1 according to implementations described herein.

FIG. 3 is a perspective view of the liner assembly and one or more flowratio controllers that can be used in the chamber of FIG. 1 according toimplementations described herein.

FIG. 4 schematically illustrates connections between one or more gasinjection inserts and one or more flow ratio controllers that can beused in the chamber of FIG. 1 according to implementations describedherein.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures. It is also contemplated that elements disclosed in oneimplementation may be beneficially utilized on other implementationswithout specific recitation.

DETAILED DESCRIPTION

Implementations of the present disclosure generally relate to using oneor more flow ratio controllers and one or more gas injection insertswith a semiconductor processing chamber. In one implementation, anapparatus includes a first flow ratio controller including a firstplurality of flow controllers, a second flow ratio controller includinga second plurality of flow controllers, and a gas injection insertincluding a first portion and a second portion. The first portion of thegas injection insert includes a first plurality of channels and thesecond portion of the gas injection insert includes a second pluralityof channels. The apparatus further includes a plurality of gas linesconnecting the first and second pluralities of flow controllers to thefirst and second pluralities of channels. One or more gas lines of theplurality of gas lines are each connected to a channel of the firstplurality of channels and a channel of the second plurality of channels.

FIG. 1 illustrates a schematic side cross-sectional view of a chamber100 according to implementations described herein. The chamber 100 maybe used to process one or more substrates, including the deposition of amaterial on an upper surface of a substrate 108. The chamber 100 mayinclude an array of radiant heating lamps 102 for heating, among othercomponents, a back side 104 of a substrate support 106 disposed withinthe chamber 100. In some implementations, the array of radiant heatinglamps 102 may be disposed over an upper dome 128. The substrate support106 may be a disk-like substrate support 106 as shown, or may be aring-like substrate support with no central opening, which supports thesubstrate from the edge of the substrate to facilitate exposure of thesubstrate to the thermal radiation of the lamps 102. In someimplementations, the substrate support 106 may include multiple arms forsupporting the substrate 108.

The substrate support 106 is located within the chamber 100 between theupper dome 128 and a lower dome 114. The upper dome 128, the lower dome114 and a base ring 136 that is disposed between the upper dome 128 andlower dome 114 generally define an internal region of the processchamber 100. The substrate 108 can be brought into the chamber 100 andpositioned onto the substrate support 106 through a loading port (notshown).

The substrate support 106 is shown in an elevated processing position,but may be vertically traversed by an actuator (not shown) to a loadingposition below the processing position to allow lift pins 105 to contactthe lower dome 114 to raise the substrate 108 from the substrate support106. A robot (not shown) may then enter the chamber 100 to engage andremove the substrate 108 therefrom through the loading port.

The substrate support 106, while located in the processing position,divides the internal volume of the chamber 100 into a process gas region156 above the substrate support 106, and a purge gas region 158 belowthe substrate support 106. The substrate support 106 may be rotatedduring processing by a central shaft 132 to minimize the effect ofthermal and process gas flow spatial anomalies within the chamber 100and thus facilitate uniform processing of the substrate 108. Thesubstrate support 106 is supported by the central shaft 132, which movesthe substrate 108 in an up and down direction 134 during loading andunloading, and in some instances, processing of the substrate 108. Thesubstrate support 106 may be formed from silicon carbide or graphitecoated with silicon carbide to absorb radiant energy from the lamps 102and conduct the radiant energy to the substrate 108.

The central window portion of the upper dome 128 and the bottom of thelower dome 114 are formed from an optically transparent material such asquartz. One or more lamps, such as an array of lamps 102, can bedisposed adjacent to and beneath the lower dome 114 in a specifiedmanner around the central shaft 132 to independently control thetemperature at various regions of the substrate 108 as the process gaspasses over, thereby facilitating the deposition of a material onto theupper surface of the substrate 108. While not discussed here in detail,the deposited material may include silicon, silicon germanium, galliumarsenide, gallium nitride, or aluminum gallium nitride.

The lamps 102 may include bulbs 141 to heat the substrate 108 to atemperature within a range of about 200 degrees Celsius to about 1600degrees Celsius. Each lamp 102 is coupled to a power distribution board(not shown) through which power is supplied to each lamp 102. The lamps102 are positioned within a lamphead 145 which may be cooled during orafter processing by, for example, a cooling fluid introduced intochannels 149 located between the lamps 102. The lamphead 145 cools thelower dome 114 due in part to the close proximity of the lamphead 145 tothe lower dome 114. The lamphead 145 may also cool the lamp walls andwalls of the reflectors (not shown) around the lamps 102.

An annular shield 167 may be optionally disposed around the substratesupport 106 and surrounded by a liner assembly 163. The annular shield167 prevents or minimizes leakage of heat/light noise from the lamps 102to the device side 116 of the substrate 108 while providing a pre-heatzone for the process gases. The annular shield 167 may be made from CVDSiC, sintered graphite coated with SiC, grown SiC, opaque quartz, coatedquartz, or any similar, suitable material that is resistant to chemicalbreakdown by process and purging gases.

The liner assembly 163 is sized to be nested within or surrounded by aninner circumference of the base ring 136. The liner assembly 163 shieldsthe processing volume (i.e., the process gas region 156 and purge gasregion 158) from metallic walls of the process chamber 100. The metallicwalls may react with precursors and cause contamination in theprocessing volume. While the liner assembly 163 is shown as a singlebody, the liner assembly 163 may include one or more liners withdifferent configurations.

As a result of backside heating of the substrate 108 from the substratesupport 106, the use of an optical pyrometer 118 for temperaturemeasurements/control on the substrate support can be performed. Thistemperature measurement by the optical pyrometer 118 may also be done onsubstrate device side 116 having an unknown emissivity since heating thesubstrate front side 110 in this manner is emissivity independent. As aresult, the optical pyrometer 118 can only sense radiation from the hotsubstrate 108 that conducts from the substrate support 106, with minimalbackground radiation from the lamps 102 directly reaching the opticalpyrometer 118.

A reflector 122 may be optionally placed outside the upper dome 128 toreflect infrared light that is radiating off the substrate 108 back ontothe substrate 108. The reflector 122 may be secured to the upper dome128 using a clamp ring 130. The reflector 122 can be made of a metalsuch as aluminum or stainless steel. The efficiency of the reflectioncan be improved by coating a reflector area with a highly reflectivecoating such as with gold. The reflector 122 can have one or morechannels 126 connected to a cooling source (not shown). Each channel 126connects to a passage (not shown) formed on a side of the reflector 122.The passage is configured to carry a flow of a fluid such as water andmay run horizontally along the side of the reflector 122 in any patterncovering a portion or entire surface of the reflector 122 for coolingthe reflector 122.

Process gases supplied from process gas supply sources 177, 179 areintroduced into the process gas region 156 through a gas injectioninsert 174 located in the sidewall of the base ring 136. The processgases may flow into one or more flow ratio controllers 171, 172 prior toentering the gas injection insert 174. The gas injection insert 174 isconfigured to direct the process gases in a generally radially inwarddirection. The one or more flow ratio controllers 171, 172 and the gasinjection insert 174 provide tuning of the flow rates and flow rateratio of the process gases which enables modulating the radial gas flowvelocity profile in the cross flow chamber 100 while keeping the totalgas flow as well as the gas partial pressure at the injection pointconstant. In addition, the one or more flow ratio controllers 171, 172and the gas injection insert 174 provide tuning of alloy composition,dopant concentration, or selectivity. The one or more flow ratiocontrollers 171, 172 and the gas injection insert 174 are described indetail in FIGS. 3 and 4. During the film formation process, thesubstrate support 106 may be located in the processing position, whichis adjacent to and at about the same elevation as the gas injectioninsert 174, allowing the process gases to flow along a flow path 173across the upper surface of the substrate 108 in a laminar flow fashion.The process gases exit the process gas region 156 (along flow path 175)through a gas outlet 178 located on the side of the chamber 100 oppositethe gas injection insert 174. Removal of the process gases through thegas outlet 178 may be facilitated by a vacuum pump 180 coupled thereto.

A purge gas may be supplied from a purge gas source 162 to the purge gasregion 158 through an optional purge gas inlet 164 (or through the gasinjection insert 174) formed in the sidewall of the base ring 136. Thepurge gas inlet 164 is disposed at an elevation below the gas injectioninsert 174. During the film formation process, the substrate support 106may be located at a position such that the purge gas flows along a flowpath 165 across the back side 104 of the substrate support 106 in alaminar flow fashion. Without being bound by any particular theory, theflowing of the purge gas is believed to prevent or substantially avoidthe flow of the process gas from entering into the purge gas region 158,or to reduce diffusion of the process gas entering the purge gas region158 (i.e., the region under the substrate support 106). The purge gasexits the purge gas region 158 (along flow path 166) and is exhaustedout of the chamber 100 through the gas outlet 178, which is located onthe side of the chamber 100 opposite the purge gas inlet 164.

Similarly, during the purging process the substrate support 106 may belocated in an elevated position to allow the purge gas to flow laterallyacross the back side 104 of the substrate support 106. It should beappreciated by those of ordinary skill in the art that the process gasinlet, the purge gas inlet and the gas outlet are shown for illustrativepurpose, since the position, size, or number of gas inlets or outletetc. may be adjusted to further facilitate a uniform deposition ofmaterial on the substrate 108.

FIG. 2 illustrates a perspective view of a liner assembly that can beused in place of the liner assembly 163 of FIG. 1 according toimplementations described herein. The liner assembly 200 is configuredfor lining a processing region within a process chamber, such as thechamber 100 of FIG. 1. The liner assembly 200 generally provides a gasinlet port 202, a gas outlet port 204, and a loading port 206. The linerassembly 200 may be nested within or surrounded by a base ring (e.g.,the base ring 136 of FIG. 1) disposed in the chamber. The liner assembly200 may be formed as an integral piece, or may comprise multiple piecesthat can be assembled together. In one example, the liner assembly 200comprises multiple pieces (or liners) that are modular and are adaptedto be replaced individually or collectively to provide additionalflexibility and cost savings due to the modular design. Modular designof the liner assembly 200 enables easy serviceability and increasedfunctionality (i.e. changing of different injectors). In oneimplementation, the liner assembly 200 comprises at least an upper liner208 and a lower liner 210 that are stacked vertically. An exhaust liner212 may be combined by part of the upper liner 208 to improve positionstability.

The upper liner 208 and the exhaust liner 212 may be cut-out to receivean injector liner 214. The injector liner 214 is coupled to one or moregas injection inserts 218. The one or more gas injection inserts 218 maybe the gas injection insert 174 shown in FIG. 1. In one implementation,one gas injection insert 218 includes a first portion 222 having aplurality of channels 220 and a second portion 224 having a plurality ofchannels 226. In one implementation, the first portion 222 and thesecond portion 224 of the gas injection insert 218 are two separate gasinjection inserts 218. One or more process gases are introduced into thechamber via the channels 220, 226.

FIG. 3 is a perspective view of the liner assembly 200 and one or moreflow ratio controllers 304, 306 that can be used in the chamber 100 ofFIG. 1 according to implementations described herein. The one or moreflow ratio controllers 304, 306 may be the one or more flow ratiocontrollers 171, 172 shown in FIG. 1. As shown in FIG. 3, the linerassembly 200 includes the injector liner 214 and one or more gasinjection inserts 218 coupled to the injector liner 214. The one or moregas injection inserts 218 are coupled to a manifold 302. The manifold302 includes a first surface 303 and a second surface 305 opposite thefirst surface 303. A first flow ratio controller 304 is coupled to thefirst surface 303 of the manifold 302, and a second flow ratiocontroller 306 is coupled to the second surface 305 of the manifold 302.A plurality of tubes 308 are disposed in the gas injection insert 218,each tube 308 may be located within a corresponding channel 220, 226(FIG. 2). The plurality of tubes 308 may be connected to the manifold302, and process gases may flow through the manifold 302 into thechamber 100 (FIG. 1) via the plurality of tubes 308.

FIG. 4 schematically illustrates connections between one or more gasinjection inserts 218 and one or more flow ratio controllers 304, 306that can be used in the chamber 100 of FIG. 1 according toimplementations described herein. As shown in FIG. 4, the gas injectioninsert 218 includes the first portion 222 and the second portion 224. Inone implementation, the first portion 222 and the second portion 224 areseparate gas injection inserts. Each portion 222, 224 includes aplurality of channels 220, 226 formed therein, and the number ofchannels 220 in the first portion 222 equals to the number of channels226 in the second portion 226. In one implementation, each portion 222,224 includes nine channels 220 a-220 i or 226 a-226 i, as shown in FIG.4. In another implementation, each portion 222, 224 includes 11channels. The first portion 222 and the second portion 224 may be mirrorimages of each other with respect to a central axis 401. The locationsof the channels 220 a-220 i in the first portion 222 and the locationsof the channels 226 a-226 i may be symmetrical with respect to thecentral axis 401. For example, the location of an inner channel 220 i inthe first portion 222 and the location of an inner channel 226 i in thesecond portion 224 are symmetrical with respect to the central axis 401.The inner channel 220 i is adjacent to the inner channel 226 i, as shownin FIG. 4.

One or more flow ratio controllers 304, 306 are connected to the gasinjection insert 218 by a plurality of gas lines. The gas lines may beany suitable lines, such as conduits or tubes, for gas or fluid to flowtherethrough. In one implementation, two flow ratio controllers 304, 306are connected to the gas injection insert 218 by the plurality of gaslines, as shown in FIG. 4. Each flow ratio controller 304, 306 includesa plurality of flow controllers, such as mass flow controllers (MFCs).In one implementation, the flow ratio controller 304 includes five flowcontrollers 402, 404, 406, 408, 410, and the flow ratio controller 306includes five flow controllers 412, 414, 416, 418, 420. The number offlow controllers in each flow ratio controller 304, 306 may be more orless than five. In one implementation, there are 22 channels formed inthe gas injection insert 218 (11 channels in each of the first andsecond portions 222, 224) and six flow controllers in each flow ratiocontrollers 304, 306.

The flow controllers 402, 404, 406, 408, 410, 412, 414, 416, 418, 420are connected to the channels 220 a-220 i, 226 a-226 i (or tubes locatedin the channels, such as tubes 308 shown in FIG. 3) by a plurality ofgas lines. The inner channel 220 i of the first portion 222 is connectedto the flow controller 410 in the flow ratio controller 304 by a gasline 422, and the inner channel 226 i of the second portion 224 isconnected to the flow controller 412 in the flow ratio controller 306 bya gas line 424. Each of the remaining flow controllers 402, 404, 406,408 in the flow ratio controller 304 is connected to two channels, onechannel in the first portion 222 of the gas injection insert 218 and theother channel in the second portion 224 of the gas injection insert 218.Each of the remaining flow controllers 414, 416, 418, 420 in the flowratio controller 306 is connected to two channels, one channel in thefirst portion 222 of the gas injection insert 218 and the other channelin the second portion 224 of the gas injection insert 218. No channel inthe gas injection insert 218 is connected to more than one flowcontroller.

For example, the flow controller 402 in the flow ratio controller 304 isconnected to a first gas line 426, which splits into two gas lines 426a, 426 b. The gas line 426 a is connected to the channel 220 a in thefirst portion 222, and the gas line 426 b is connected to the channel226 b in the second portion 224. The flow controller 404 in the flowratio controller 304 is connected to a second gas line 428, which splitsinto two gas lines 428 a, 428 b. The gas line 428 a is connected to thechannel 220 c in the first portion 222, and the gas line 428 b isconnected to the channel 226 d in the second portion 224. The flowcontroller 406 in the flow ratio controller 304 is connected to a thirdgas line 430, which splits into two gas lines 430 a, 430 b. The gas line430 a is connected to the channel 220 e in the first portion 222, andthe gas line 430 b is connected to the channel 226 f in the secondportion 224. The flow controller 408 in the flow ratio controller 304 isconnected to a fourth gas line 432, which splits into two gas lines 432a, 432 b. The gas line 432 a is connected to the channel 220 g in thefirst portion 222, and the gas line 432 b is connected to the channel226 h in the second portion 224. The flow controller 410 in the flowratio controller 304 is connected to the fifth gas line 422, which isconnected to the inner channel 220 i in the first portion 222. The flowcontroller 412 in the flow ratio controller 306 is connected to thesixth gas line 424, which is connected to the inner channel 226 i in thesecond portion 224. The flow controller 414 in the flow ratio controller306 is connected to a seventh gas line 434, which splits into two gaslines 434 a, 434 b. The gas line 434 a is connected to the channel 220 hin the first portion 222, and the gas line 434 b is connected to thechannel 226 g in the second portion 224. The flow controller 416 in theflow ratio controller 306 is connected to an eighth gas line 436, whichsplits into two gas lines 436 a, 436 b. The gas line 436 a is connectedto the channel 220 f in the first portion 222, and the gas line 436 b isconnected to the channel 226 e in the second portion 224. The flowcontroller 418 in the flow ratio controller 306 is connected to a ninthgas line 438, which splits into two gas lines 438 a, 438 b. The gas line438 a is connected to the channel 220 d in the first portion 222, andthe gas line 438 b is connected to the channel 226 c in the secondportion 224. The flow controller 420 in the flow ratio controller 306 isconnected to a tenth gas line 440, which splits into two gas lines 440a, 440 b. The gas line 440 a is connected to the channel 220 b in thefirst portion 222, and the gas line 440 b is connected to the channel226 a in the second portion 224.

The flow ratio controller 304 is connected to a first gas source, suchas the gas source 177 (FIG. 1), and the flow ratio controller 306 isconnected to a second gas source, such as the gas source 179 (FIG. 1).The first gas source provides a first gas (or gas mixture) A to the flowcontrollers 402, 404, 406, 408, 410 of the flow ratio controller 304,and the second gas source provides a second gas (or gas mixture) B tothe flow controllers 412, 414, 416, 418, 420 of the flow ratiocontroller 306. The first gas A and the second gas B are directed to thechannels 220 a-220 i and 226 a-226 i (or tubes located inside of thechannels) by the gas lines 426, 428, 430, 432, 422, 424, 434, 436, 438,440. The first gas A and the second gas B are alternately flowingthrough the channels 220 a-220 i and 226 a-226 i. For example, the firstgas A flows through the channel 220 a in the first portion 222, and thechannel 220 a is the outermost channel. The second gas B flows throughthe channel 220 b, which is adjacent to the channel 220 a, in the firstportion 222. In other words, gases flowing through adjacent channels areprovided from different gas sources, or different gases flow throughadjacent channels. Due to the positioning of the two flow controllers onopposite surfaces of the manifold 302, flow of the A and B gases can beinterleaved in an alternating fashion into the channels 220.

The one or more flow ratio controllers 304, 306, the one or more gasinjection inserts 218, and the plurality of gas lines connecting theflow ratio controllers 304, 306 to the gas injection insert 218 as shownin FIG. 4 enables the use of two different gases or gas mixtures (A andB) with alternating injection points A-B-A-B-A-B-A-B-A=B-A-B-A-B-A-B-A-B(=denotes a central axis, such as the central axis 401 shown in FIG. 4).All of the injection points for one gas or gas mixture are grouped intopairs, except for the inner injection point, such as the inner channel220 i or 226 i, which is not paired with another channel. By separatingthe injection points into two groups (A and B), two independent gas flowprofiles can be utilized to tune alloy composition (e.g. silicon versusgermanium, silicon versus carbon, germanium versus tin) orresistivity/doping concentration or selectivity (deposition precursorversus etch precursor). For example, in one implementation, the firstprocess gas A is a silicon containing precursor and the second processgas B is a germanium containing precursor. The alloy composition ofsilicon and germanium in the deposited silicon germanium layer can betuned by adjusting the flow controllers 402, 404, 406, 408, 410 relativeto the flow controllers 412, 414, 416, 418, 420. In anotherimplementation, the first process gas A is a silicon containingprecursor and the second process gas B is a dopant such as a arseniccontaining dopant. The dopant concentration in the deposited dopedsilicon layer can be tuned by adjusting the flow controllers 402, 404,406, 408, 410 relative to the flow controllers 412, 414, 416, 418, 420.In addition, thickness non-uniformity of the deposited layer isimproved. Use of a flow ratio controller that includes a number of flowcontrollers allows easy flow tuning among the various flow controllers.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. An apparatus, comprising: a first flow ratiocontroller including a first plurality of flow controllers, the firstflow ratio controller configured to receive a first gas through a firstinlet; a second flow ratio controller including a second plurality offlow controllers, the second flow ratio controller configured to receivea second gas through a second inlet different than the first inlet; agas injection insert including a first portion and a second portion,wherein the first portion includes a first plurality of channels and thesecond portion includes a second plurality of channels; and a pluralityof gas lines connecting the first and second pluralities of flowcontrollers to the first and second pluralities of channels, wherein:gas lines of a first subset of the plurality of gas lines are eachindividually connected between a flow controller of the first pluralityof flow controllers and two channels to provide the first gasindependently from the second gas, wherein one of the two channels isfrom the first plurality of channels and the other of the two channelsis from the second plurality of channels; and gas lines of a secondsubset of the plurality of gas lines are each individually connectedbetween a flow controller of the second plurality of flow controllersand another two channels to provide the second gas independently fromthe first gas, wherein one of the another two channels is from the firstplurality of channels and the other of the another two channels is fromthe second plurality of channels.
 2. The apparatus of claim 1, whereinthe first plurality of channels include eleven channels and the secondplurality of channels include eleven channels.
 3. The apparatus of claim2, wherein the first plurality of flow controllers include five flowcontrollers and the second plurality of flow controllers include fiveflow controllers.
 4. The apparatus of claim 3, wherein the plurality ofgas lines include eight gas lines, and each of the eight gas lines isconnected to a distinct flow controller of the first and secondpluralities of flow controllers.
 5. The apparatus of claim 1, whereinthe first plurality of channels include eleven channels and the secondplurality of channels include eleven channels.
 6. The apparatus of claim5, wherein the first plurality of flow controllers include six flowcontrollers and the second plurality of flow controllers include sixflow controllers.
 7. The apparatus of claim 6, wherein the plurality ofgas lines include ten gas lines, and each of the ten gas lines isconnected to a distinct flow controller of the first and secondpluralities of flow controllers.
 8. An apparatus, comprising: a firstflow ratio controller including a first plurality of flow controllers,the first flow ratio controller configured to receive a first gasthrough a first inlet; a second flow ratio controller including a secondplurality of flow controllers, the second flow ratio controllerconfigured to receive a second gas through a second inlet different thanthe first inlet; a gas injection insert including a first portion and asecond portion, wherein the first portion includes a first plurality ofchannels and a first inner channel and the second portion includes asecond plurality of channels and a second inner channel; a plurality ofgas lines connecting the first and second pluralities of flowcontrollers to the first and second pluralities of channels, wherein:gas lines of a first subset of the plurality of gas lines are connectedbetween a flow controller of the first plurality of flow controllers andtwo channels to provide the first gas independently from the second gas,wherein one of the two channels is from the first plurality of channelsand the other of the two channels is from the second plurality ofchannels, and wherein a first gas line of the first subset of theplurality of gas lines connects a first flow controller of the firstplurality of flow controllers to the first inner channel; and gas linesof a second subset of the plurality of gas lines are connected between aflow controller of the second plurality of flow controllers and anothertwo channels to provide the second gas independently from the first gas,wherein one of the another two channels is from the first plurality ofchannels and the other of the another two channels_is from the secondplurality of channels, and wherein a second gas line of the secondsubset of the plurality of gas lines connects a second flow controllerof the second plurality of flow controllers to the second inner channel.9. The apparatus of claim 8, wherein the first plurality of channelsinclude eight channels and the second plurality of channels includeeight channels.
 10. The apparatus of claim 9, wherein the firstplurality of flow controllers include four flow controllers and thesecond plurality of flow controllers include four flow controllers. 11.The apparatus of claim 8, wherein the first plurality of channelsinclude ten channels and the second plurality of channels include tenchannels.
 12. The apparatus of claim 11, wherein the first plurality offlow controllers include five flow controllers and the second pluralityof flow controllers include five flow controllers.
 13. An apparatus,comprising: a chamber, comprising: an upper dome; a lower dome; a basering disposed between the upper dome and the lower dome; and a gasinjection insert located within the base ring, wherein the gas injectioninsert includes a first portion and a second portion, wherein the firstportion includes a first plurality of channels and the second portionincludes a second plurality of channels, the first plurality of channelsand the second plurality of channels configured to introduce gas flowasymmetrical with respect to a central axis; a first flow ratiocontroller including a first plurality of flow controllers, the firstflow ratio controller configured to receive a first gas through a firstinlet; a second flow ratio controller including a second plurality offlow controllers, the second flow ratio controller configured to receivea second gas through a second inlet different than the first inlet; anda plurality of gas lines connecting the first and second pluralities offlow controllers to the first and second pluralities of channels,wherein: gas lines of a first subset of the plurality of gas lines areeach individually connected between a flow controller of the firstplurality of flow controllers and two channels to provide the first gasindependently from the second gas, wherein one of the two channels isfrom the first plurality of channels and the other of the two channelsis from the second plurality of channels; and gas lines of a secondsubset of the plurality of gas lines are each individually connectedbetween a flow controller of the second plurality of flow controllersand another two channels to provide the second gas independently fromthe first gas, wherein one of the another two channels is from the firstplurality of channels and the other of the another two channels is fromthe second plurality of channels.
 14. The apparatus of claim 13, whereinthe first plurality of channels include nine channels, the secondplurality of channels include nine channels, the first plurality of flowcontrollers include five flow controllers, and the second plurality offlow controllers include five flow controllers.
 15. The apparatus ofclaim 14, wherein the plurality of gas lines include eight gas lines,and each of the eight gas lines is connected to a distinct flowcontroller of the first and second pluralities of flow controllers. 16.The apparatus of claim 13, wherein the first plurality of channelsinclude eleven channels and the second plurality of channels includeeleven channels.
 17. The apparatus of claim 16, wherein the firstplurality of flow controllers include six flow controllers and thesecond plurality of flow controllers include six flow controllers. 18.The apparatus of claim 17, wherein the one or more gas lines of theplurality of gas lines include ten gas lines, and each of the ten gaslines is connected to a distinct flow controller of the first and secondpluralities of flow controllers.
 19. The apparatus of claim 13, furthercomprising: a liner assembly, wherein the liner assembly comprises: anupper liner; a lower liner; an exhaust liner; and an injector liner. 20.The liner assembly of claim 19, wherein the injector liner is coupled tothe gas injection insert.